1. Field of the Invention
The present invention relates to a disk subsystem, and a power source control apparatus for a disk subsystem and/or a disk subsystem apparatus that is operated uninterruptedly.
2. Related Background Art
An existing disk subsystem apparatus is required to operate uninterrupted 24 hours a day, 365 days a year, and to have high density/large capacity through expansion of stored data. Accordingly, the following technology is conceivable for a power source control apparatus of a disk system apparatus.
For example, a disk subsystem apparatus includes in its basic structure a main power source, a power source control circuit, a power source for the power source control circuit, a hard disk drive (HDD) control logic section that controls data transfer, an HDD drive section that drives HDDs with fiber channel interface ports, and a fiber channel interface.
In the basic operation with this structure, when an apparatus switch is turned on while the power source control circuit is supplied with power from the power source for the power source control circuit, power is supplied from the main power source to the HDD control logic section and the HDD drive section, which makes the disk subsystem apparatus operable. The control by the HDD control logic section allows read/write access via the fiber channel interface to the HDDs of the HDD drive section.
However, with this structure if a failure occurs in any one of the parts, read/write access to the HDDs becomes impossible, such that the uninterrupted operation cannot be continued. Further, due to the lack of expandability in the HDD drive section, such an apparatus cannot meet demands for large capacity.
In view of the above, first, in order to make uninterrupted operation of the apparatus possible, the apparatus must be able to operate normally without any decline in its functions or performance even when a part of its components fails during operation, the apparatus must be able to specify the failed part and report it, and the failed part must be replaceable while the apparatus operates normally.
To achieve this, the basic structure described above must be a double-sided structure, the power source system needs to be provided with a separate power source boundary between the two sides; and the data transfer system that is the fundamental function of the apparatus needs to use two systems of fiber channel interface ports provided on the HDDs in order to make the path from the HDD control logic section to the HDDs redundant (i.e., duplicated) for read/write accesses to the HDDs. As a result, even if a failure occurs somewhere on one side of either the power source system or the data transfer system, the other side can guarantee operation. Further, the HDDs should have a RAID structure, which will allow rebuilding of a failed disk.
Secondly, with regard to achieving high density/large capacity, the HDD control logic section and the HDD drive section should be provided independently of each other to provide expandability to the HDD drive section; through this, the HDD drive section can be expanded (or reduced) as necessary.
For example, in the power source system, a new power source boundary may be provided between the HDD control logic section and the HDD drive section. The HDD control logic section may have a power source control circuit for the HDD control logic section and a dedicated power source for the control circuit, while the HDD drive section may have a power source for the HDD drive section, as well as a control circuit to control the power source of the HDD drive section under the control of the HDD control logic section, and a dedicated power source for the control circuit. A dedicated interface for power source control between the HDD control logic section and the HDD drive section is required on each expansion section.
In the data transfer system, a fiber channel interface between the HDD control logic section and the HDD drive section, a fiber channel control interface for the HDD control logic section to control the connection configuration of the HDDs, a fiber channel control circuit on the HDD drive section, and a fiber channel interface between the HDD drive section and the HDDs are provided; and the HDD drive section including the expansion sections need to be controlled by the HDD control logic section and a fiber channel loop can be formed.
Moreover, in order to make uninterrupted operation possible even during the process of expanding the system, all of the structures described above must be made redundant (i.e., duplicated).
The following became apparent as a result of the inventors' examination of the power source control apparatus of a disk subsystem apparatus described above.
For example, in order to realize uninterrupted operation and high density/large capacity in a disk subsystem apparatus, the disk subsystem apparatus must be provided with the structure described above. To achieve this, there would be two sides to the power source boundary of the HDD control logic section and to the power source boundary of the HDD drive section's power source control section, as well as a power source boundary between the HDD control logic section and the HDD drive section. This results in a complex power source boundary structure, increases the number of parts in the power source system, and makes the apparatus large.
As a result, there may be more factors that can impede uninterrupted operation, such as rising failure rate and falling reliability of the apparatus; increasingly complex power source boundary as the HDD drive section expands, making maintenance work more difficult; and greater number of errors committed in maintenance work to repair failures. In addition, the price of the apparatus may become higher as a result of increased number of parts. Furthermore, due to the fact that power is supplied to the HDD drive section with the power on/off operation of the HDD control logic section on a power source control by power source control basis regardless of the actual operational status of the apparatus, non-operating parts become powered even if the HDD drive section is in a non-operating state; consequently, power is wasted and the power consumption of the apparatus as a whole may not correspond to its operations.